Problem on Application load balancer with rule: Health check only responds on the default rule

Hi everyone I have 3 microservices running on an ECS cluster. Each microservice is launched by a Fargate task. Each microservice runs in its own Docker container.

• Microservice A responds on port 8083.
• Microservice B responds on port 8084.
• Microservice C responds on port 8085.

My configuration consists of two public subnets, two private, an internet gateway and a NAT, as well as two security groups, one for fargate services and one for ALB. On the security groups I have enabled inbound traffic on all ports.

I have defined a listner for the ALB that responds on port 80 and wrote some path-based rules to route requests to the appropriate target group (every target group is a Target type) :

Only the health check of the target group that responds to the default rule responds ( but I suspect it all happens randomly) , and consequently only the service reachable on port 8083 works

The remaining target groups are unreachable. What you notice is that in the "Registered Target" section the assigned IP addresses change continuously. For example:

But every time IP assigned it generates a timeout. It can happen quite randomly that a certain IP address is registered correctly.

These are the ECS configurations of one of the unresponsive services:

What is the problem and how can I solve it? Thank you.

UPDATE1

I tried to add a new instance for microservice A. For the new IP (10.0.0.137) the health check is not responding. After a few minutes, the provisioning of a new IP (10.0.0.151) appears and it is registered correctly:

UPDATE2

It is really strange behavior. All services are now connected correctly, after several hours of failed attempts. It looks like an IP address assignment problem. Before finding the correct address, AWS makes several attempts with different IP addresses until it randomly finds the correct one. These are the CIDRs of my PRIVATE subnets

• private_subnets = ["10.0.0.128/28", "10.0.0.144/28"]
• public_subnets = ["10.0.0.0/28", "10.0.0.16/28"]

While these are the IPs that connected successfully:

1. 10.0.0.136 (micorservice A istance1)
2. 10.0.0.151 (micorservice A istance2)
3. 10.0.0.153 (micorservice A istance3)
4. 10.0.0.152 (micorservice B)
5. 10.0.0.142 (Microservice C)